1. Field of the Invention
The present invention relates to an apparatus, system and methods of administering a fluid such as a medicated fluid in metered amount such as a unit dose to treat respiratory ailments. In particular, the invention relates to disposable aerosol generators, wherein the aerosols are generated via vaporization.
2. Description of Related Art
Aerosols are useful in a variety of applications including treatment of respiratory ailments. Various techniques for generating aerosols are disclosed in U.S. Pat. Nos. 4,811,731; 4,627,432; 5,743,251; and 5,823,178.
In particular, two distinct methods for delivery of medicated fluid in the form of an aerosol have been developed. In accordance with one method, a pharmaceutically active drug is dispensed in a low boiling point propellant (e.g., chloro-fluoro-carbon (CFC) or (HFA)) loaded in a pressurized canister from which the drug/propellant formulation may be released by the use of a device generally known as a metered dose inhaler. Once released the propellant evaporates and particles of the drug are inhaled by the patient. The other method involves the use of a nebulizer which creates an inhalable mist of fine particles from a solution or suspension of a drug. Both methods are hindered by significant problems relating to administering the proper dose.
In drug delivery applications, it is typically desirable to provide an aerosol having average mass median particles diameter of less than 2 microns to facilitate deep lung penetration. Additionally, it is desirable, in certain drug applications, to deliver medicaments at high flow rates (i.e., above 1 milligram per second). Devices for controlling the flow rate of an aerosol are known. For example, U.S. Pat. No. 4,790,305 concerns controlling the particle size of a metered dose of aerosol for delivery to the walls of bronchi and bronchioles by filling a first chamber with medication and a second chamber with air such that all of the air is inhaled prior to the inhaling of medication, and using flow control orifices to control the flow rate. U.S. Pat. No. 4,926,852 relates to metering a dose of medication into a flow-through chamber that has orifices to limit the flow rate to control particle size. U.S. Pat. No. 3,658,059 discloses a baffle that changes the size of an aperture in the passage of the suspension being inhaled to select the quantity and size of particles delivered. A problem associated with these devices is that they process the aerosol after it is generated and are inefficient and wasteful.
To meet the requirements of administering a fluid in the form of an aerosol and to overcome the disadvantages of the prior art, it is an object of the present invention to provide an aerosol generator which vaporizes the fluid at a controlled flow rate regardless of the fluid""s viscosity.
It is another object of the invention to obtain uniform vaporization of the fluid that is expelled from the aerosol generator.
It is a further object of the invention to provide a disposable aerosol generator which can deliver a metered dose of the fluid. By delivering individual single doses of medicated fluid it is possible to avoid contamination of the fluid, thereby negating the need for bacteriostatic compounds within the drug formulation.
It is yet another object of the invention to provide a disposable cartridge which can incorporate a package having therein multiple disposable aerosol generators, each of which provides a single shot delivery, as required by the user.
Other objects and aspects of the present invention will become apparent to one of ordinary skill in the art upon review of the specification, drawings and claims appended hereto.
According to one aspect of the invention, a disposable aerosol generator is provided which is adapted for use with an inhaler device which includes a heater arranged to volatilize fluid stored in the disposable aerosol generator. The aerosol generator comprises a disposable body having a sealed chamber and an outlet wherein first and second layers of material define the chamber. The chamber accommodates a predetermined volume of a fluid which is expelled through the outlet when the fluid in the chamber is volatilized by the heater.
According to another aspect of the invention, an inhaler device is provided which is usable with the disposable aerosol generator mentioned above, the inhaler device including a heater arranged to heat the fluid in the chamber so as to expel volatilized fluid from the outlet. The heater can comprise a layer of resistance heating material on a substrate which includes an opening located adjacent the outlet. In order to form the outlet, an opening device such as a piercing element can be provided which is adapted to pierce the first and/or second layer to form the outlet.
According to a further aspect of the invention, a method of using the inhaler device mentioned above is provided, the method including severing the first and/or second layer so as to form the outlet and activating the heater so as to volatilize the fluid in the chamber and expel the volatilized fluid through the outlet. According to a preferred method, the disposable body includes a series of spaced apart aerosol generators and the method includes moving the disposable body relative to the inhaler device so as to locate a first one of the aerosol generators at a position where the heater can heat the fluid in the chamber of the first aerosol generator and volatilize the fluid therein. The severing can be carried out by driving a piercing member through the first and/or second layer and the outlet can be located adjacent a passage of a dispensing member such that the volatilized fluid formed by the heater is expelled into the passage after passing through the outlet.